Verapamil Cardiac L-type — FRCA Primary MCQ
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Correct answer: A — Cardiac L-type calcium channels (SA and AV nodes)
Verapamil primarily blocks cardiac L-type calcium channels particularly in the SA and AV nodes causing negative chronotropy / dromotropy / and inotropy. It is a Class IV antiarrhythmic used for SVT. Dihydropyridines (nifedipine / amlodipine) preferentially block vascular smooth muscle L-type channels causing vasodilation with minimal cardiac effect.
Reference: Peck Hill Williams 2014 Pharmacology for Anaesthesia and Intensive Care